The present invention is generally directed to a heat sink assembly for the removal of heat from a heat generating electronic device such as a microprocessor. The present invention is directed more specifically to a heat sink assembly which includes a small electric fan for creating an airflow along and through the heat transfer surface area of the heat sink.
A typical heat sink includes a solid base and a plurality of fins or pins which extend from the base. Heat is dissipated from the heat sink by free convection. The surface heat transfer characteristics of the heat sink are further enhanced by forced convection. In forced convection, an airflow is directed along and through the heat transfer surface element of the heat sink. Initially, forced convection was achieved by the implementation of blowers or fans within the cabinet or housing of a computer system. The advent of more powerful and high heat generating microprocessors rendered a general forced convection system obsolete. In order to cool the new microprocessors adequately, more sophisticated multiple level fan systems were required. This creates additional noise and consumption of space at the expense of electronic components. Also, the new systems were no longer reliable. These problems were solved to some degree by the development of fan driven heat sink packages. Such a package includes a fan which is mounted directly to a heat sink which, in turn, is mounted to a microprocessor. In one type of fan driven heat sink package, some of the fins or portions of the fins are removed to create a space for the fan. This saves space and enables the fan to be positioned close to the base of the heat sink. However, the loss of fin area and the limitation of airflow to the base and to the lower portions of the fins results in a substantial loss in cooling efficiency. For other fan driven heat sink assemblies, the fan is mounted directly on top of the fins or pins of the heat sink. In this type of assembly, air from the fan is directed to the pins or fins which are located below the fan at an initial air velocity. Air from the fan can exit the assembly quite readily through the spaces between the fins or pins just outside of the fan housing. Very little airflow is developed along the fins or pins and the airflow has very little velocity. The prior art fan driven heat sink assemblies have provided minimal improvement in cooling efficiency over general fan driven forced convection systems. These and other difficulties experienced with the prior art devices have been obviated by the present invention.
It is, therefore, a principle object of the present invention to provide a fan driven heat sink assembly which is capable of developing a substantial air pressure between the fan and the heat sink and capable of developing a high uniform velocity airflow along the surfaces of the fins of the heat sink to provide substantial improvement in heat dissipation efficiency.
Another object of the invention is to provide fan driven heat sink assembly which has a substantially higher fin surface area, which enhances the heat dissipation efficiency which is created by the positive or forced convection airflow along the surfaces of the fins.
A further object of the invention is the provision of a method of making a fan driven heat sink assembly which results in a higher cooling fin density and increased fin surface area.
With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.